The Jonah Scan

Hypertrophic Cardiomyopathy (HCM) is a silent killer and it claimed our beloved hospital cat, Jonah, very suddenly one Monday evening. It is in his memory that MAVH highly recommends THE JONAH SCAN.
THE JONAH SCAN is a baseline, affordable echocardiogram for our feline patients. This brief ultrasound screen of the heart will assess the thickness of the ventricular wall in order to diagnose HCM before there is a problem.

But first some background…

Any disease that primarily impacts the heart muscle is known as cardiomyopathy. In Jonah’s case, he was found to have had hypertrophic cardiomyopathy (HCM). This disease can affect all cats ranging in age from 3 months to 17 years, but young-to-middle aged MALE cats (Jonah!) seem to be affected most frequently.

HCM causes the walls of the heart’s left ventricle to thicken and become stiff. This in turn decreases the space available for the blood and leads to the inability of the heart’s walls to relax appropriately “between beats”. As a consequence, blood backs up into the left atrium, causing its walls to stretch. Eventually, blood backs up in the lungs causing left-sided heart failure.

In more severe cases, blood remains stagnant in the left atrium and can form clots that can break off and travel to other parts of the body, causing muscular weakness or hind limb paralysis.

The degree of thickening of the heart muscle’s walls ultimately determines the clinical severity of the disease.

Most causes of HCM are unknown. It can be genetic in some breeds, such as Maine Coon, Persian, and Ragdoll cats, but HCM can occur in ANY cat. It can occur also secondary to hyperthyroidism, hypertension, or aortic stenosis.

Unfortunately, early clinical signs such as lethargy and exercise intolerance are often missed (oh, just a catnap!), and what really gets your attention may be your cat’s increased respiratory rate, open-mouth breathing, panting and/or (sudden) collapse.

Interestingly, 80% of affected cats have heart murmurs that are discovered on routine physical examination. Milder forms may progress and worsen, or remain static for years.

In summary, THE JONAH SCAN is beneficial for all cats but especially if a heart murmur has been detected upon examination, and will provide valuable baseline information for the management and monitoring of HCM, a silent killer.

-Kelly Dickinson, DVM (Special Interest Feline Medicine)

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